Space Elevator Climbing Construction Method

ABSTRACT

A method of constructing an elevator core structure for a space elevator tower. The actively stabilized space elevator tower is a pneumatically pressurized structure formed from flexible sheet material. This construction method comprises raising a core segment with a climbing construction elevator that grips the outer surface of the core structure, sliding the core segment on top of the core structure on a horizontal track, and actively adjusting the core structure&#39;s center of mass. The freestanding tower can be used for launch activities, tourism, observation, energy generation, scientific research, and communications.

FIELD

This invention relates to space elevators, and more particularly to a method of constructing a freestanding space elevator tower.

BACKGROUND

In order to access space or near space, payloads must gain significant potential and kinetic energy. Traditionally, regions above 50 km in altitude can only be accessed using rocketry, where mass is expelled at high velocity in order to achieve thrust in the opposite direction. This process is extremely inefficient as rockets must counter the gravitational force during the flight by carrying mass in the form of propellant and must overcome atmospheric drag. In contrast, if a payload is hauled to space or near space along an elevator system, the work done is significantly less as no expulsion mass must be carried to do work against gravity, and lower ascent speeds in the lower atmosphere can virtually eliminate atmospheric drag. Elevator cars' motion may also be powered remotely by electrical or inductive means, eliminating the need to carry any fuel.

It has previously been proposed, most famously by Arthur C. Clarke in his 1978 novel, The Fountains of Paradise, that a space elevator could be constructed using a cable and counter-balanced mass system. For Earth's gravity and spin rate, such a solution requires a cable of at least 35,000 km in length and a counter balance mass similar to a small asteroid. Such a system could be constructed by launching the cable into space or manufacturing it in situ and lowering it into contact with Earth. However, the technological obstacles that must be overcome, including the construction of a cable with suitable strength characteristics or the in-space construction of the apparatus, have not been realized since the concept was popularized by Clarke. Known materials are simply not strong enough to enable the construction of a cable of that length that would even be capable of supporting its own weight.

SUMMARY

The present invention is a method of constructing a space elevator tower. The actively stabilized space elevator tower has a segmented elevator core structure, each segment being formed of at least one pneumatically pressurized cell. The method of constructing the tower comprises raising a core segment with a climbing construction elevator that grips the external surface of the existing elevator core structure. The core segment then slides on top of the existing elevator core structure on a horizontal track on the climbing construction elevator. The center of mass of the elevator core structure is actively adjusted to maintain the elevator core structure over its footprint.

The space tower can be used for the delivery of payloads to at least one platform or pod above the planetary surface for the purposes of space launch or for the recovery of a rocket stage. The space elevator tower may also be used to deliver equipment, personnel and other objects or people to at least one platform or pod above the surface of the Earth. While the described space elevator tower can provide access to lower altitude regions, the space elevator tower can also be scaled to access altitudes above, for example, 15 km, the typical ceiling altitude for commercial aviation. The space elevator tower can be further scaled to provide direct access to altitudes above 200 km and with the gravitation potential of Low Earth Orbit (LEO).

Although ascending to an altitude significantly below 35,000 km will not place a payload in Earth orbit, a platform or pod supported by the space elevator tower has significant advantages over a surface-based launch platform. While surface-based rockets must be designed to overcome atmospheric air resistance, launch from a high-altitude platform has no such requirement, and, consequently, existing space equipment such as an orbital transfer stage or conventional upper stage can be used to insert payloads directly into Earth orbit. Ideally, payloads should be raised to the highest feasible altitude before launching in order to maximize the energy advantages; however, the energy advantages for space flight are readily leveraged above 5 km.

A platform or pod supported by the space elevator tower also has significant advantages over orbiting satellite platforms. Geographically fixed, but providing access to regions of space closer to the surface than geostationary orbit, elevator platforms provide the ideal means to communicate over a wide area and to conduct remote sensing and tourism activities. As a tourist destination, the elevator platforms provide stations located at fixed attitudes from the surface for observation. The elevator platforms provide the means to safely access a region of space with a view extending hundreds of kilometers.

The space elevator tower may also provide a near-surface observation platform with oversight over a fixed geographical area. Such platforms can be used for observation, remote sensing and communications. Small systems may be mobile and delivered to sites for temporary applications for example to provide temporary communications towers typically between 25 m and 150 m. The space elevator tower may also provide a platform for energy generation. Used with an elevator component equipment may be accessed and maintained during operation. Used without an elevator component, equipment may be installed only during the construction of the apparatus.

The invention provides a method of constructing the freestanding space elevator tower. The method allows the adding of core segments using a climbing construction elevator that grips the surface of the existing elevator core structure and raises the segment. The core segment then slides on top of the existing elevator core structure on a horizontal track on the climbing construction elevator. The invention includes active adjustment of the center of mass of the elevator core structure when a core segment is added.

Further aspects and advantages of the invention will appear from the following descriptions taken together with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates a method of constructing the space elevator tower 10. It is to be appreciated that the construction methods of the present invention are not limited to the following example, and that features of the following configuration may be combined to produce further variations of the construction method without departing from the scope of the present invention.

DETAILED DESCRIPTION OF THE DRAWING

FIG. 1 shows a construction approach where core segments 14 are raised by means of a climbing construction elevator 899 that grips the external surface of the existing elevator core structure 12 as it raises and installs segments section by section. Advantageously, core segments 14 equipped with stabilization systems (not shown) may be energized by means of an umbilical connector 897 such that the new core segment 14 may be raised completely above the construction elevator 899 and installed on the existing elevator core structure 12 by means of a horizontal track (not shown) installed on the top of the construction elevator 999. The center of mass of the combined system may be adjusted actively during the core segment installation in order to maintain it over the elevator core structure's 12 surface footprint and to provide support for the elevator core structure 12 in the presence of external disturbance torques. 

1. A method of constructing an elevator core structure for a space elevator tower, the method comprising: a) raising a core segment with a climbing construction elevator that grips the outer surface of the existing elevator core structure; b) sliding the core segment on top of the existing elevator core structure on a horizontal track on the climbing construction elevator; and, c) during steps (a) and (b), actively adjusting the center of mass of the existing elevator core structure to maintain the elevator core structure over its footprint. 